The present invention relates generally to a method for financing multimedia content through advertising by playing back advertising blocks between uses of the content, and in particular to a method for financing multimedia content in which code elements of a key are embedded in predefined locations in the advertising blocks.
Methods for financing multimedia content through advertising by playing back advertising blocks between uses of the content are known in general from advertising-financed free TV, where they are widespread and are used by advertisers who wish to finance the presentation of useful data by presenting mixed-in sequences of advertising blocks.
The distribution of media is often financed by advertising breaks. This is not a problem today in the area of television, because the customer cannot “fast forward” a television broadcast. The custom of “zapping” is taken into account by broadcasters by extensive synchronization of advertising.
The situation is different in the area of recorded content, e.g., when television broadcasts are recorded on videocassettes, where the user often has the option of bypassing the advertising by fast forwarding the videotape until the advertising is terminated. This problem occurs mainly in the video area but is also conceivable for other media (CDs, DVDs).
This problem obtains a new dimension with a development which is bundled by the “TV Anytime” standardization initiative (http://www.tv-anvtime.org/): In the future, television sets, video recorders and/or set-top boxes will contain memory media (e.g., hard drives with a capacity of 50 to 100 Gigabytes) which will make it possible to record and play back the content simultaneously as desired. This will make it much easier for the customer to skip the advertising breaks:                The customer will record about 15 minutes of the broadcast.        Then he will begin to watch it.        Whenever an advertising break occurs, he will skip the break and will start again after the break.        
Protection of content was an important concern of the DVD standardization forum (www.dvdforum.com). Therefore, an encryption system (content scrambling system, CSS) has been specified for DVD. According to this system, a header preceding each data block on the DVD contains the title key encrypted with the disk key. Using this title key and a few extra bits, it is then possible to decrypt the content of the file.